Field of the Invention
The present invention relates to cooling of structures within the skull of a mammal, and more particularly to cooling of brain tissue.
Description of the Related Art
Lowering the temperature of the brain is known to reduce the chances of brain tissue damage when oxygenated blood supply to the brain is diminished as may occur during ischemic or anoxic events for example during stroke, cardiac arrest, respiratory arrest, suffocation, drowning, strangulation, electrocution or any other head or body trauma that disrupts the flow of oxygenated blood to the brain.
Clinical investigators have reported that mild and moderate hypothermia can be neuroprotective to reduce brain injury and decrease death and disability for a variety of acute brain injuries following severe head trauma, cardiac arrest, stroke and neonatal asphyxia. The neuroprotective benefits of hypothermia have been linked to the time to initiate cooling after injury, depth of cooling and re-warming rate. Clinical studies indicate that the temperature range associated with better outcomes appears to be 32-35° C. and has to be achieved as quickly as possible. However, cooling the whole body below 34° C. can cause complications including shivering, sclerema, skin erythema, renal failure, coagulopathy, pulmonary hypertension, myocardial ischemia and others. Consequently, to limit the deleterious effects of whole body cooling, only mild hypothermia, in which the brain temperature is decreased to 34° C. has been applied, whereas it is known that additional neuroprotection can be achieved by cooling the brain further and quickly at the outset.
Selective cooling of the head, and more particularly the brain region may provide a neuroprotective benefit while avoiding the deleterious effects of whole body hypothermia. Functional solutions along this line have been proposed, for example, in U.S. Pat. No. 5,261,399 (issued 16 Nov. 1993), U.S. Pat. No. 5,913,885 (issued 22 Jun. 1999), U.S. Pat. No. 5,916,242 (issued 29 Jun. 1999), U.S. Pat. No. 6,312,453 (issued 6 Nov. 2001), U.S. Pat. No. 6,682,552 (issued 27 Jan. 2004), U.S. Pat. No. 8,308,786 (issued 13 Nov. 2012), U.S. Pat. No. 8,512,280 (issued 20 Aug. 2013) and US Patent Application Publication Nos. 20060112698 (published 1 Jun. 2006), 20060276552 (published 7 Dec. 2006), 20130331915 (12 Dec. 2013) and International Application Publication No. WO2010148372 (23 Dec. 2010). However, each of these solutions suffers from insufficient cooling, insufficient localization of cooling, use of a toxic coolant and/or deleterious effects on skin contact points.
Accordingly, there is a continuing need for alternative head cooling systems.